/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.apache.iotdb.confignode.procedure.scheduler;

import org.apache.iotdb.confignode.procedure.Procedure;

import java.util.ArrayDeque;

/**
 * Lock Queue for procedure of the same type
 */
public class LockQueue {
    private final ArrayDeque<Procedure<?>> deque = new ArrayDeque<>();

    private Procedure<?> lockOwnerProcedure = null;

    public boolean tryLock(Procedure<?> procedure) {
        if (lockOwnerProcedure == null) {
            lockOwnerProcedure = procedure;
            return true;
        }
        return procedure.getProcId() == lockOwnerProcedure.getProcId();
    }

    public boolean releaseLock(Procedure<?> procedure) {
        if (lockOwnerProcedure == null || lockOwnerProcedure.getProcId() != procedure.getProcId()) {
            return false;
        }
        lockOwnerProcedure = null;
        return true;
    }

    public void waitProcedure(Procedure<?> procedure) {
        deque.addLast(procedure);
    }

    public int wakeWaitingProcedures(ProcedureScheduler procedureScheduler) {
        int count = deque.size();
        while (!deque.isEmpty()) {
            procedureScheduler.addFront(deque.pollFirst());
        }
        return count;
    }
}
